ASO Agglutination Test Flashcards
ASO
Anti-streptolysin O
streptococci characteristics
gram positive spherical, ovoid, lancet shaped organism
catalase negative that are often seen in pairs or chains under microscope
what is the basis of the division of streptococci into different serogroups?
cell wall components
what major proteins are contained on the outermost cell wall components?
M and T protein
these determine the serotype or serogroup of the streptococcus spp.
M and T protein
interior to the protein layer that divides streptococci into 20 defined groups
group-specific carbohydrate
20 defined groups of streptococci
A-H, K-V
some biologically important streptococcus belong to what groups
group A, B, C, D
group of s. pyogenes
group A
group of s. galactiae
group B
group of s. dysgalactiae
group C
group of s. bovis
group D
group of enterococcus
group D
one of the most common and ubiquitous pathogenic bacteria and causes a variety of infection
s. pyogenes
diseases caused by s. pyogenes
scarlet fever, bacterial acute glomerulonephritis, acute rheumatic fever
what is the major virulence facto of s pyogenes of group A?
m protein
what is the function of m protein
inhibits phagocytosis by inhibiting adhesion process
other virulence factors of s pyogenes
exotoxins
responsible for the rash seen in scarlet fever and also appear to contribute to pathogenicity
pyrogenic exotoxins A, B, and C
enzymes produced by streptococcus
streptolysin O, DNAse B, hyaluronidase, NADase, streptokinase
the most diagnostically important antibodies
ASO, anti-DNAse B, anti-NADase, anti-hyaluronidase
Group A streptococcus infection is seen in conditions like
scarlet fever, acute glomerulonephritis, acute rheumatic fever, necrotizing fasciitis, streptococcal shock syndrome
what is the principle of ASO agglutination test
passive agglutination in which antigen is accompanied by a carrier particle
what does the ASO agglutination test detect?
antibody
what is the significant titer for adults in ASO agglutination test
240 Todd unit
what is the significant titer for children in ASO agglutination test?
320 Todd units
what is preferred sample for the ASO agglutination test?
patient’s serum sample
what kind of method is ASO procedure?
qualitative method
what to do if we receive a positive reaction?
proceed with quantitative method (serial dilution)
PROCEDURE for ASO agglutination test
same as CRP
what does the positive reaction of ASO agglutination test indicate?
> 200 Todd units
what is the limit of sensitivity of ASO agglutination test?
200 (same as dilution factor)
what does the negative reaction for the serial dilution indicate?
200 Todd units
what is the normal level for ASO?
<200 Todd units
ASO latex reagents
a suspension of polystyrene latex particles sensitized with streptococcal exoenzyme
ASO positive control
a stabilized human serum containing ASO reactive with ASO latex reagent
ASO negative control
a stabilized human serum containing ASO nonreactive with ASO latex reagent
what is used as a reagent’s preservative?
0.1% sodium azide
diagnosis of the probability for sequelae S. pyogenes infection
ASO tube test
dilution used for ASO tube test
compound dilution
principle of ASO tube test
neutralization/ enzyme inhibition test
what is the positive reaction for ASO tube test?
no hemolysis
what is the significant titer for ASO tube test?
166 Todd units
antigen excess
prozone effect
antibody excess
postzone
